[R] How to retrieve a vector of a data.frame's variable attributes?

[Bacou, Melanie]

Hi,

I have a data.frame with 100 variables and I have assigned a "label",
"units" and "category" attribute to each variable. I would like to reorder
the variables in the data.frame by the "category" attributes but can't find
a way.

For example, the first variable is:

> attributes(hh$aez)
$levels
[1] "coastal"  "forest"   "savannah"

$class
[1] "labelled" "factor"  

$label
[1] ecological zone
93 Levels: 10 quantiles of welfare  ... year of the interview

$units
[1] class
24 Levels: '05 PPP USD / year cedis / year cedis /year class geo-1 ... years

$category
[1] geography
7 Levels: agriculture demography design expenditure geography ... welfare

I have tried:

hh <- hh[, order(attr(hh, "category"))]
hh <- hh[, order(attr(hh[, 1:100], "category"))]
hh <- hh[, order(attr(dimnames(hh), "category"))]

but all the right-hand side assignments above return NULL.

Thanks very much for your help with this simple task!

--Mel.



_______________________
 Melanie Bacou
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